Re: LMbench2.0 results

[Hugh Dickins <hugh@veritas.com>]

On Sun, 8 Sep 2002, Andrew Morton wrote:
> 
> We need to find some way of making vm_enough_memory not call get_page_state
> so often.  One way of doing that might be to make get_page_state dump
> its latest result into a global copy, and make vm_enough_memory()
> only get_page_state once per N invokations.  A speed/accuracy tradeoff there.

Accuracy is not very important in that sysctl_overcommit_memory 0 case
e.g. the swapper_space.nr_pages addition was brought in at a time when
it was very necessary, but usually overestimates now (or last time I
thought about it).  The main thing to look out for is running the same
memory grabber twice in quick succession: not nice if it succeeds the
first time, but not the second, just because of some transient effect
that its old pages are temporarily uncounted.

Hugh